Electrically insulating devices



Dec. 22, 1959 ABRAMS 2,918,521

ELECTRICAL-LY INSULATING DEVICES Filed Feb. 11, 1957 2 Sheets-Sheet l 21461 5 F iii A m mm 1' T R. ABRAMS 2,918,521

ELECTRICALLY INSULATING DEVICES Filed Feb. 11, 1957 2 Sheets-Sheet 2 ELECTRICALLY INSULATING DEVICES Ralph Abrams Sharon, Mass, assignor to Cambridge Thermionic Corporation, Cambridge, Mass, a corporation of Massachusetts Application February 11, 1957, Serial No. 639,576 6 Claims. (Cl. 174-152) This invention relates to insulating mounts for use in electrical installations, generally speaking of the lead through and stand off types which can be fastened in apertures of supports such as panels or chassis and which are capable of carrying and receiving therewithin conducting and connecting means.

The principal object of the invention is to provide devices of the above character which are especially suited for insulation with electrically superior insulating materials of the types exemplified by polyfluoroethylene polymers which have little elastic tendency or memory to return to an original shape after having been more or less suddenly deformed, or at least a tendency to become permanently deformed under continuous stress below a certain pressure, but which on the other hand have a comparatively high tendency to flow upon application of a higher pressure, due tolow internal or molecular friction. Such materials are ill suited for inco-rporation in conventionally designed and fabricated devices of the above type so that it was found to be quite important to find techniques for providing, in a commercially acceptable way, assemblies which permit the safe use of such insulating materials in the simplest possible manner while taking advantage of the above-mentioned superior electrical characteristics thereof.

Other objects are to provide improved insulated assemblies or insulating mounts which can be manufactured with a minimum amount of molding, machining and assemblmg operations, to provide improved insulated stand off and lead through insulators which incorporate unconfined insulating material of the above type without danger of losing shape and which lend themselves for assembly with metal parts according to simple and inexpensive mass production techniques, to provide such devices which can be easily assembled or mounted on panels of widely varying types and thickness, and to provide insulating devices of this type which lend themselves especially well to miniaturizing.

A brief summary indicating the nature and substance of the invention, for attaining the above objects, characteri zes its principal aspects as follows.

- Insulating mounts according to the invention have a metal insert which is freely surrounded by an insulator body having an axial cavity between two transverse faces which correspond to transverse shoulders extending from the insert, and are manufactured by preforming the average distance between the faces of the body slightly greater than the average distance between the shoulders of the insert, by performing theaverage outer diameter of the insert slightly greater than the inner diameter of the cavity, and by preforming the average outer diameter of the shoulders appreciably greater than the inner diameter of the cavity; and by assembling the insulator body and the insert by axially pressing the insert into the cavity of the insulator with the forward shoulder passing the cavity opening andpenetrating the cavity until the faces and shouldersinterengage while the outside of the insulator body 'is being kept under .restr'aint against deformation 2 during such assembly; whereby-the cavity is temporarily deformed by the flow of the material around the forward shoulder during assembly at comparatively high pressure without permanent deformation of the insulator, and whereby the insulator firmly engages the insert without elastic return after removal of the restraint.

In important practical embodiments, the insulator body has a closed recess with or without a widened cavitywith faces for receiving flange portions of the metal insert, which flange portions define the above-mentioned shoulders of the insert. In other embodiments, the body recess is open on both sides and the transverse outer faces receive shoulders of the insert. In further embodiments, the insert has anchor shaped projections with flattened sides or polygonal portions, for preventing rotatory disengagement; the anchor portions can provide the afore mentioned shoulders which prevent axial disengagemenh;

and also the aforementioned polygonal shapes which pre: vent rotatory disengagement of insulator body and metal insert.

In a practically very important aspect, the insulator recess is preformed without faces on cavities and the insert with its preformed flanges and shoulder portions is pressed thereinto while the insulator 'body is confined within a form; in accordance with this aspect of the invention, the confined insulator body is caused to flow around the metal portions that are pressed thereinto whereas, upon release of the inserting pressure and removal of the insulator with the metal insert from the form, the insulator indefinitely retains its shape, interiorly closely fitting the insert while exteriorly preserving its that of the original outer configuration that conforms to form wherein it was confined during assembly. 7

In embodiments wherein the recess of the insulator body has no internal cavity faces or is otherwise not especially preformed to receive the forward shoulder of the insert, the face for the latter is formed during assembly.

These and other objects and aspects of novelty in addi tion to those contained in the above summary of thenature and the objects of the invention will appear from the following description of several typical embodiments This description reillustrating its novel characteristics. fers to drawings in which Fig. 1 is an elevation of the metallic insert or pin of the insulating mount according to one embodiment of the invention;

Fig. 2 is a longitudinal section of the insulating shell component of that embodiment;

Fig. 3 is an elevation showing the components according to Figs. 1 and 2 respectively, during assembly, also showing in longitudinal section a tool which is used for purposes of the method for assembling the two components;

Fig. 4 is a representation similar to Fig. 3, but with the metal pin fully inserted and with the insulating shell,

partly in longitudinal section to indicate the placement of the metal core therein;

Fig. 5 is a side elevation of the finished device, indicating its fixation to a panel;

Fig. 6 shows the metal insert as well as the'insulating body, the latter in longitudinal section, of a second embodiment of the invention and also a step of the method of assembly, with the metal pin not yet contacting the insulator body;

Fig. 7 shows the fully assembled device according to this embodiment of the invention, with the device not yet removed from the form; I

Fig. 8 is an elevation similar to Fig. 5 of the fully assembled device, mounted on a panel orsimilar support;

Figs. 9, 10 and 11 are top view, side elevation and embodiment of the invention;

Fig. 12 is a longitudinal section of the insulating body of this third embodiment;

Fig. 13 shows the fully assembled device, still within the form, similar to Fig. 4; v V

Fig. 14 is a section on lines 1414 of Fig. 13; and

Fig. 15 is a side elevation of the fully assembled device.

Figs. 1 and 2 illustrate the essential components of insulating devices according to the invention, namely an insulator body 21 and an insert pin 22. The insulator body 21 is generally speaking of cylindrical shape and has in this embodiment a flange 21.1, a cylindrical recess 21.2 and a cylindrical cavity 21.3 which is somewhat wider than the recess 21.2. In this embodimentthe insulator body also has a bottom 21.4 and the recess 21.2 is preferably provided with a chamfer 21.6.

The insert pin 22 has a shank portion 22.1 between a collar 22.2 and achamfered flange 22.3. The shank has a polygonal portion, in this instance a knurled section 22.4. -On the otherside of the collar 22.2 is a lug portion 22.6 which may be provided with annular ridges 22.7 for facilitating the soldering thereto of electrical conductors. It will be evident that the solder lug portion 22.6 can be replaced by other suitable conductor connecting means.

Figs. 3 and 4 illustrate the assembly process according to the invention, which takes place as follows.

S The insulator body 21 is inserted into a form or confiningjig 26 which may be simply a tube section 27 weldedor otherwise fastened to a baseplate 28 having a recess 28.1 that fits the chamfered bottom 21.4 of the insulator body 21. The pin is then placed with its chamfer 22.3on the chamfer 21.6 of the insulator body and thereupon pressed home by means of a hollow pressing tool 29 which can be a simple pin with a tubular recess 29.1 that loosely fits the lug or other outer-portion of the insert pin. Fig. 3 indicates the pin in the course of being pressed into the insulator body, in the direction of arrow m. After having been stopped by the contacting of flanges 21.1 and 22.2, the pressing tool is withdrawn from the completed assembly, as indicated by arrow 11 of Fig. 4. The assembled mount is then removed from the jig which is easily possible since the insulating material ofthe above described type slides easily and with little friction. Instead of first separately seating the pin on the insulator, it can be moved onto it with the tool as will be described with reference to Fig. 6 for another embodiment. As indicated above, Fig. 3 illustrates the intermediate stage during which the insert pin is forcibly pressed into the insulating material until the flange 22.3 reaches the cavity 21.3 and so to speak snaps thereinto or anchors itself therein, as shown in Fig. 4.

It was found that the above characterized polymer material flows easily around the flange 22.3 and the polygonal section 22.1 during the comparatively rapid insertion of the pin at comparatively high pressure within the form 26 and that, due to the confinement of the insulator body during this pressurable insertion, the external configuration is not appreciably distorted, although portions thereof might be displaced during the insertion process.

The completed mount is shown in Fig. which also illustrates the possibility of affixing it to a panel such as indicated at p, simply by press fitting it into a perforation thereof.

The embodiment illustrated in Figs. 6, 7 and 8 is quite similar to theone described above, with-the difference that the insert pin has here two solder lugs, representing by way of example plural conduit attachment devices, one on each side of the insulator body, which requires the latter to be open on both sides. The two components are indicated at 31 and 32 of Fig. 6 which also illustrates a modified firstassembly step. The insert pin 32 has again a core portion 32.1 with a polygonal section 32.4, and an anchor collar 32.3. The two solder lugs are indicated at 32.6 and 32.7, and the rearward collar In this instance the insulator body is put into the forming jig as before, but the insert 39 is initially fed to the pressing tool wherein it can be held by slight friction and, if desirable, with the aid of a slight vacuum applied through perforation 39.1. The assembly operation proper takes place essentially as described above with reference to Figs. 3 and 4, namely by pressing the insert 32 into the core 31 until the collar 32.2 rests on the core flange 31.1. For obvious reasons, the form 36, which corresponds to the form 26 indicated in Figs. 3 and 4, has in this instance an opening 37 accommodating the solder lug flanges 32.71 but forming a shoulder 37.1 leading into the main cavity which just accommodates the insulator body 31. The pressure for sealing the collar 32.2 on the flange 31.1 suflices to snap the collar 32.3 underneath the lower face 31.2 of the insulator.

Fig. 6 illustrates the assembly step just prior to the insertion of the metal pin 32 into the polymer body 31, and Fig. 7 shows the assembly within the form, prior to lifting the tool 39 with the assembly, in the direction of arrow n.

Due to the slight surface friction of the polymer material involved, the finished assembly can be removed from the form 36 by pulling the tool and holder 39 upwardly, whereupon the completed assembly can be easily pulled from the recess 39.2, after releasing the vacuum at 39.1 and, if desirable, applying slight air pressure instead. If the process is carried out as described above with reference to Figs. 3 and 4, with the completed assembly remaining in the jig, then the former can be ejected from the latter by means of a pushing tool such as indicated at :4), moving in the direction of arrow 0. It will be evident that the above described process steps can be performed by means of conventional automatic machinery as well as by hand.

Fig. 8 shows the completed mount and the manner in which it can be affixed to a panel p, and it will be noted that the anchor flange 32.3 is here outside of the insulator body which is held between this anchor flange 32.3 and the upper flange 32.2.

Figs. 9 to 15 illustrate a third embodiment wherein the insert pin 52 has a single connecting portion such as a solder lug 52.6 and wherein the insulator body is of the general type shown in Figs. 1 and 2, with closed bottom. However, instead of incorporating a cylindrical anchor flange such as 22.3 of Fig. l in combination with a polygonal portion such as the knurled part 22.4 of Fig. l

for preventing axial displacement, this embodiment has one or more portions which serve the purpose of both anchor flange and polygonal portion. As shown in Figs. 10, 11 and 13, the insert pin 52 has a core portion 52.1 and an attachment portion 52.6, and therebetween a collar 52.2. The core portion has two flattened anchor portions 53 and 54 which, as indicated in Figs. 9 and 11 are obtained by appropriately profiling round stock and then machining it to obtain the flat faces indicated at 54.1 and 54.2 of Fig. 11.

The insulator body 51 has a flange 51.1, a recess 51.2 and a bottom 51.4. It was found that the assembling method according to the invention does not necessarily require cavities such as 21.3 of Fig. 2 for receiving the anchor portions or portion of the insert and, accordingly, the cavity 51.2 is here simply a smooth recess.

The assembly operation is quite similar to that described above with reference to Figs. 3, 4, 6 and 7. Assuming that a loose pressing tool is used as in Figs. 3 and 4, Fig. 13 indicates the step just following that indicated in Fig. 4, prior to removal of the completed assembly from the form 56. Figs. 13 and 14 indicate how the polymer material flows practically completely around the anchor portions 53 and 54, while Fig. 15 indicates that no deformation is noticeable upon removal of the final assembly from the form 56. As mentioned before, the end of the pressing step manifests itself by the resting of the flange 52.2 on the flange 51.1 of the insulator body.

It will be noted that, while not all steps of assembly are shown for each one of the embodiments, a complete and detailed illustration of the assembly steps is provided by the figures read in the sequence Fig. 6; Fig. 3 and Fig. 13; Fig. 4; and Fig. 15.

The relative dimensions of the inserted portions of the pin and of the corresponding portions of the insulator body are of some significance. These should slightly vary, but no definite rule for exact dimensional relationships can be given. However the following values for the dimensions of an actual embodiment, indicated in Figs. 1 and 2 will be sufficient as a guide for the proper preforming of the interengag'ng proportions of such assemblies, as follows: a=0.277", b=0.282", r=0.095", s=0.089", t=0.l25".

While it is difficult to develop a fully satisfactory theoretical explanation of the behavior of the above characterized polymers in assemblies and assembly processes of this'type, it appears that according to the invention, the flowing properties at elevated pressures within confined spaces can be taken advantage of for momenta;ily deforming the insulator body during assembly whi'e the lack of elasticity and fiow at lower pressures prevent a change of configuration subsequently to removal from the confining means and long range deformation thereafter so that not only is the outer shape of the insulator body preserved, but the interior configuration which was established during the pressurable assembly is likewise permanently preserved; at any rate it has been confirmed by ample experience that composite articles which are preformed and assembled in the manner described with reference to the above three embodiments retain their shape and effectiveness through any use for which s ch permanency can be reasonably expected. This behavior makes it possible to dispense with metallic members which wholly or partly confine the outer surface of insulator bodies made of the herein utilized polymer material. While the outside configuration of the insulator body is always essentially preserved, a very slight essentially uniform increase in diameter of the insulator might take place; it will be evident that this can be easily taken care of by appropriate preforming of the insulator.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims. More particularly, it will be evident that certain features of the above described embodiments can be interchanged or combined, for example double ended mounts can be made with anchors according to Figs. 9 to 14, insulator bodies according to Fig. 2 can be preformed intern :lly smooth as in Fig. 12, and preformed cavities as in Fig. 2 can be provided for anchors according to Fig. 10. Such modifications and particularly also the preformed dimensions of the insulator body depend a good deal upon the shapes and relative sizes in each individual embodiment; the insulator cavity should be dimensioned such that the insulating material which is displaced by penetrating parts of the insert will be approximately accom modated in cavity portions that are not occupied by insert portions.

I claim:

1. The method of making a composite article such as an insulating mount which has a metal insert with a core between transverse shoulder means, within an insulator body with an axial recess between two transverse faces at least one of which extends at the opening of the recess and being made of insulating material which has physical properties characteristic of polyfiuoroethylenes such as appreciable tendency to flow due to low internal friction and little tendency elastically to return after deformation to an original shape, said method comprising the steps of: preforming the distance between said faces to be slightly greater than the distance between said shoulder means; preforming the average diameter of said core to be slightly greater than the diameter of said recess; preforming the periphery of said shoulder means to be appreciably greater than the diameter of said recess; and axially pressing said insert into said recess of said insulator body with the forward shoulder means passing said opening face of the recess and penetrating the body until the second shoulder means engages the opening face, the outside of the insulator body being restrained to its preformed configuration against deformation during such assembly; whereby the recess is temporarily deformed by the flow during assembly of said insulating material around the forward shoulder means wtihout permanent deformation of the insulator body, and the insulator body firmly engages the core and the shoulder means without elastic return upon removal of the restraint.

2. The method of making a composite article such as an insulating mount which has a metal insert with a core between transverse shoulder means, within an insulator body with an axial recess extending essentially smoothly from a transverse face at an opening of the recess and being made of insulating material which has physical properties characteristic of polyfluoroethylenes such as appreciable tendency to flow due to low internal friction and little tendency elastically to return after deformation to an original shape, said method comprising the steps of: preforming said recess and that portion of said insert which is embedded in the cavity such that the volume of said portion is approximately equal to the volume of said recess prior to assembly; and axially pressing said insert into said recess of said insulator body with one shoulder means passing said opening face of the recess and penetrating the body until the other shoulder means engages said opening face, the outside of the insulator body being restrained to its preformed outside configuration against deformation during such assembly; whereby the recess is temporarily deformed by the flow during assembly of said insulating means around the forward shoulder means without permanent outside deformation of the insulator body, and the insulator body firmly engages the core and the shoulder means without elastic return upon removal of the restraint.

3. A composite article such as an insulating mount, comprising: an insulator body of material having physical properties characteristic of polyfluoroethylenes such as appreciable tendency to flow due to low internal friction and little tendency elastically to return after deformation to an original shape, said insulator having an axial recess between two transverse faces at least one of which extends at the opening of the recess; and a metal insert having a core between two transverse shoulder means which extend outwardly from the core; the distance between said faces being slightly greater than the preformed distance between said shoulder means, the preformed average diameter of said core being slightly greater than the preformed diameter of said recess, the preformed average diameter of said shoulder means being appreciably greater than the preformed diameter of the recess, and said insulator body being conditioned through assembly with said metal insert by axially pressing said insert into said recess of said insulator body with the forward shoulder means passing said opening face of the recess and penetrating the body until the second shoulder means engages the opening face, while restraining the outside of the insulator body to its preformed configuration against deformation during such assembly; whereby the recess is temporarily deformed by the flow during assembly of said insulating material around the forward shoulder means without permanent deformation of the insulator body, and the insulator body firmly engages the core and thershoulder means without elastic return upon removal of the restraint.

4. A composite article such as an insulating mount, comprising: an-insulator body ofmaterial having physical properties characteristic of polyfluoroethylenes such as appreciable tendency to flow due to low internal friction and little tendency elastically to return after deformation to an original shape, said insulator having an axial recess and an enlarged cavity at one end of the recess between two transverse faces one extending at the opening of the recess and the other face extending between the recess and the cavity; and a metal insert having a core between a transverse shoulder and an end flange; the preformed distance between said faces being slightly greater than the preformed distance between said shoulder and said flange, the preformed average diameter of said core being slightly greater than the preformed diameter of said recess, the preformed average diameter of said flange being appreciably greater than the preformed diameter of said recess but slightly smaller than that of said cavity, and said insulator body being conditioned through assembly with said metal insert by axially pressing said insert into said recess of said insulator body with said flange passing said opening face of the recess and penetrating the body until thesecond shoulder engages the opening face and the flange engages said other face, while restraining the outside of the insulator body to its preformed configuration against deformation during such assembly; whereby the recess is temporarily deformed .by the flow during assembly of said insulating material around the flange without permanent deformation of the insulator body, and the insulator body firmly engages the core, the flange and the shoulder without elastic return upon removal of the restraint.

5. A composite article such as an insulating mount, comprising: an insulator body of material having physical properties characteristic of polyfluoroethylenes such asappreciable tendency to flow due to low internal friction andlittle tendency elastically to return after deformation to an original shape, said insulator having an axial bore between two transverse faces at the openings of the bore; and a metal insert having two connecting means one on each side of a core between two transverse shoulders which extend outwardly from the core; the preformed distance between said faces being slightly greater than the preformed distance between said shoulders, the preformed average diameter of said core being slightly greater than the preformed diameter of said bore, the preformed average diameter of said shoulders being appreciably greater than the preformed diameter of said bore, and said insulator body being conditioned through assembly with said metal insert by axially pressing said insert into saidbore of said insulator body with the forward shoulder pass ing an opening face of the bore and penetrating the body until the second shoulder engages the opening face and the forward shoulder reaches the other face, while restraining the outside of the insulator body to its preformed configuration against deformation during such assembly; whereby the recess is temporarily deformed by the flow during assembly of said insulating material around the forward shoulder without permanent deformation of the insulator body, and the insulator body firmly engages the core and the shoulders without elastic return upon removal of the restraint.

6. A composite article such as an insulating mount, comprising: an insulator body of material having physical properties characteristic of .polyfluoroethylenes such as appreciable tendency to flow due to lowiinternal friction and little tendency elastically to return after deformation to an original shape, said insulator having an axial recess between two transverse faces one at the opening of the recess and the other forming the bottom thereof; and a metal insert having a core between a transverse shoulder and an anchor flange .which extend outwardly from the core, the anchor flange having a flattened portion; the preformed distance between said faces being appreciably greater than the preformed distance between saidshoulder and said flange, the preformed average diameter of said core being slightly greater than the preformed diameter of said recess, the preformed average diameter of said shoulder and said flange being appreciably greater than the preformed diameter of said recess, and said insulator body being conditioned through assembly with said metal insert by axially pressing said insert into said recess of said insulator body with the anchor flange passing said opening face of the recess and penetrating the body until the shoulder engages the opening face, while restraining the outside of the insulator body to its preformed configuration against deformation during such assembly; whereby the recess is temporarily deformed by the flow during assembly of said insulating material around the anchor flange which becomes embedded therein without permanent deformation of the insulator body, andthe insulator body firmly engages the core and the shoulder and flange without elastic return upon removal of the restraint.

References Cited in the file of this patent UNITED STATES PATENTS 2,785,219 Rudner Mar. 12, 1957 

5. A COMPOSITE ARTICLE SUCH AS AN INSULATING MOUNT, COMPRISING: AN INSULATOR BODY OF MATERIAL HAVING PHYSICAL PROPERTIES CHARACTERISTIC OF POLYFLUOROETHYLENSES SUCH AS APPRECIABLE TENDENCY TO FLOW DUE TO LOW INTERNAL FRICTION AND LITTLE TENDENCY ELASTICALLY TO RETURN AFTER DEFORMATION TO AN ORIGINAL SHAPE, SAID INSULATOR HAVING AN AXIAL BORE BETWEEN TWO TRANSVERSE FACES AT THE OPENINGS OF THE BORE; AND A METAL INSERT HAVING TWO CONNECTING MEANS ONE ON EACH SIDE OF A CORE BETWEEN TWO TRANSVERSE SHOULDERS WHICH EXTEND OUTWARDLY FROM THE CORE; THE PREFORMED DISTANCE BETWEEN SAID FACES BEING SLIGHTLY GREATER THAN THE PREFORMED DISTANCE BETWEEN SAID SHOULDERS, THE PREFORMED AVERAGE DIAMETER OF SAID CORE BEING SLIGHTLY GREATER THAN THE PREFORMED DIAMETER OF SAID BORE, THE PREFORMED AVERAGE DIAMETER OF SAID SHOULDERS BEING APPRECIABLY GREATER THAN THE PREFORMED DIAMETER OF SAID BORE, AND SAID INSULATOR BODY BEING CONDITIONED THROUGH ASSEMBLY WITH SAID METAL INSERT BY AXIALLY PRESSING SAID INSERT INTO SAID BORE OF SAID INSULATOR BODY WITH THE FORWARD SHOULDER PASSING AN OPENING FACE OF THE BORE AND PRNETRATING THE BODY UNTIL THE SECOND SHOULDER ENGAGES THE OPENING FACE AND THE FORWARD SHOULDER REACHES THE OTHER FACE, WHILE RESTRAINING THE OUTSIDE OF THE INSULATOR BODY TO ITS PREFORMED CONFIGURATION AGAINST DEFROMATION DURING SUCH ASSEMBLY; WHEREBY THE RECESS IS TEMPORARILY DEFORMED BY THE FLOW DURING ASSEMBLY OF SAID INSULATING MATERIAL AROUND THE FORWARD SHOULDER WITHOUT PERMANENT DEFORMATION OF THE INSULATOR BODY, AND THE INSULATOR BODY FIRMLY ENGAGES THE CORE AND THE SHOULDERS WITHOUT ELASTIC RETURN UPON REMOVAL OF THE RESTRAINT. 